Compact plate-fin heat exchangers are used to lower the temperature of one fluid by using a second fluid passing in close proximity. Common heat exchangers generally come in three different flow configurations which are illustrated in FIGS. 1A-1C. FIG. 1A illustrates a cross-flow configuration where a fluid is passed through a top plate-fin configuration in one direction while a second fluid is passed through the lower plate-fin configuration in a substantially perpendicular direction. These non-planar intersecting flows allow for the excessive heat in one flow path of a fluid to be transferred to the flow path of the other fluid by conduction of the heat through the plates and fins. FIG. 1B shows a parallel flow configuration where one fluid enters a side of one set of plate-fin configurations while another fluid enters separate interleaved plate-fin configurations that have an entry point oriented at a top edge near the side entry point of the first fluid. The fluids flow in adjacent non-planar parallel paths for a period of time and then exit in a corresponding manner. A thin wall separator maintains the distinct flow paths for each fluid and prevents their intermixing. In any event, the flow paths intersect one another and the heat carried by one of the fluids is transferred to the other fluid by heat conduction through the separating walls. FIG. 1C shows a counterflow configuration which is similar in construction to the parallel flow configuration; however, one of the fluid flows through one set of the plate-fin configurations is reversed. In each of these embodiments, and independent of their use or flow configuration, the compact plate-fin heat exchangers use a relatively thin wall to separate the two fluids to facilitate heat transfer.
As shown in FIGS. 1A-C, and in related prior art devices, a first plate-fin configuration is arranged in a plane and the other plate-fin configuration is adjacently positioned in a parallel plane that overlaps or crosses over the other plate-fin configuration. As noted, the plate-fin layers are only typically separated by a thin wall of material. Accordingly, as a first fluid passes through one plate-fin configuration heat is absorbed by the components thereof and transferred through the separating thin wall to the adjacent plate-fin configuration and absorbed by a second fluid. As such, the overlapping of the different plate-fin configurations and associated chambers facilitates the heat transfer between the two fluids. In order to improve heat transfer from one fluid to the other, the flow paths may include multiple layers as shown in FIGS. 1B and 1C so that they overlap and/or intersect one another. In other words, the layers of the different flow paths are interleaved with one another so as to facilitate the heat transfer process.
Although the aforementioned configurations have been widely adopted and are successful in their stated purpose, it is believed that they also have a number of shortcomings. The thin walls are prone to leakage over time which causes cross-contamination of the fluid materials and which is detrimental to the overall system which associated with the heat exchanger. As such, relatively lower pressures are used to prevent damage to the separator walls. By not being able to use higher pressures, the exchangers have reduced effectiveness in moving the fluids to their intended end use. It is also believed that the size of the known plate-fin heat exchangers can be prohibitive for use in systems with limited space.
Therefore, there is a need in the art for heat exchangers which eliminate cross-contamination between the fluids and which can operate at higher pressures. There is also a need to efficiently transfer heat without any loss in performance, and there is a need to provide these features in a reduced size without sacrificing the effectiveness of the configuration.